Originally Posted By: Grace_Jones
I'm just looking for the best. With a VW spec oil (504.00/507.00 aka prosche C30) there are loads of choices, whereas trying to find a true fully synthetic (or even ester synthetic) with the ford specs (913C or 913D) is difficult as there dont seem to be many.
How about this definition of "best" - the best oil is the one that is recommended and approved by the manufacturer. I am not saying this means it is the lowest pour point, highest flash point, lowest Noack or nicest odour, but that the OEM is convinced enough to recommend this oil.
If you don't go with that, then maybe the best oil is the one that meets the OEM's specification closest. Well, since we don't get access to specification test results, we have to be guided by the presence (or absence) of the specification on the oil's label or data sheet. The whole point of specifications and approvals is to avoid the need for individuals to try and work out for themselves which oil might be suitable (or not).
As you have stated (and bobbydavro has endorsed), 913-D is the latest spec for this engine type. It contains 11 physical/chemical tests, 3 corrosion/oxidation tests and 9 engine tests (comprising a total 28 different examination parameters). It covers wear, corrosion, sludge, piston deposits, TBN retention, varnish, oil consumption and other demands. Any formulator who has successfully navigated this minefield and achieved an oil which passes all of the tests will certainly have made sure VI and pour point were appropriate to the application.
There is no way for an enthusiastic amateur (no offence to any reader intended) to know how VI, HTHS, pour point, MRV or any other parameter will affect a given engine. In truth even professionals wrestle with sometimes fickle engine tests and their capricious appetites. For every opinion you get, there will be a counter-opinion, then a debate, then another option, then an agreement with the first one, then some anecdotal 'evidence' and finally no consensus at all. When you are choosing between decent oils you are unlikely to go far wrong so pick one that meets your needs and enjoy the rest of the day!